The principal objectives of this project are to purify and characterize human serum proteins (enzymes) implicated in the detoxification of bacterial endotoxins and to identify the major endproducts of the detoxification reaction. Purification of detoxifying proteins and of the major endproducts of detoxification will be achieved by various column chromatographic, immunochemical and gel electrophoretic techniques. It is intended also to isolate and characterize a protein component from the rabbit macrophage which has been implicated in detoxification.